class Calculator(object):
    def __init__(self, number):
        self.number = number
    def __add__(self, other):
        self.number = self.number + other
        return self.number
    def __sub__(self, other): 
        self.number = self.number - other
        return self.number
    def __mul__(self, other):
        self.number = self.number * other
        return self.number
    def __truediv__(self, other): 
        self.number = self.number / other
        return self.number

calculator = Calculator(10)
print(calculator + 5)
print(calculator - 5)
print(calculator * 5)
print(calculator / 5)